ME. H. M. BEEN^AED ON EECENT POEITID^. 129 



budding into two genera, Heteropora (= the modern genus 

 Madrepora) and Madrepora^ Etr. This latter consisted of two 

 subgenera, Madrepora-phyllopora (=Astr£eopora, de Biv.) and 

 Madrepora-porites, which was a heterogeneous group consisting 

 of Montipores, Stylophores, Alveopores, with a few true Poritids. 



Dana * was the first to found the family Poritidae, of equal 

 value with and closely allied to the family Madreporidse. It 

 contained two genera, 'Pontes and G-oniopora. 



This arrangement of Dana's was, in the main, accepted by 

 Milne-Edwards and Haime in 1851. The Poritidae, enlarged by 

 the addition of many more genera, constituted, together with a 

 very large family the MadreporidsB, the great section Madre- 

 poraria Perforata, as opposed to the greater bulk of the remaining 

 Stony Corals, which were grouped as Madreporaria Aporosa. This 

 recognition of the structure of the coral-skeleton as a feature of 

 fundamental taxonomic importance is the chief merit of the work 

 of these authors, which is the last comprehensive attempt to 

 classify the whole coral system. It was, however, hardly to be 

 expected that this first attempt to solve the difficult morphological 

 problems presented by the coral-skeleton would be successful. 

 It is not, therefore, surprising to find that every advance in our 

 knowledge of corals has led to some sweeping revision of Milne- 

 Edwards and Haime's system. At the present day only two of 

 its five original sections can be said to have held their own, viz., 

 the two most important, the Madreporaria Aporosa and M. Per- 

 forata f. That these two are now in their turn on the eve of 

 modification, the extent of which cannot yet be predicted, because 

 the researches which render revision necessary are still too recent, 

 will, it is hoped, be made clear in the following pages. Criticisms 

 of details have not been wanting, but they have mainly referred 

 to the relative positions of families or genera. 



No change has, so far, been made affecting the position of the 

 Poritidse, which is the matter we have especially in hand in this 

 paper. The only expressed doubt as to their aflBnity with the 

 Madreporidfe with which I am acquainted is in the recent work 

 of Miss Ogilvie J, who found it impossible to decide whether the 

 two families were or were not related. 



* ' Zoophytes,' 1848. 



t See Martin Duncan's revision]of the system in the Journ. Linn. Soc, Zool. 

 xriii. 1884, p. 3. 



X Phil. Trans, vol. 187, 1896, p. 327. 



